Renal outer medullary potassium (ROMK) channel is an important K⁺ excretion channel in the body, and K⁺ secreted by the ROMK channels is most or all source of urinary potassium. Previous studies focused on the ROMK channels of thick ascending limb (TAL) and collecting duct (CD), while there were few studies on the involvement of ROMK channels of the late distal convoluted tubule (DCT2) in K⁺ excretion. The purpose of the present study was mainly to record the ROMK channels current in renal DCT2 and observe the effect of high potassium diet on the ROMK channels by using single channel and whole-cell patch-clamp techniques. The results showed that a small conductance channel current with a conductance of 39 pS could be recorded in the apical membrane of renal DCT2, and it could be blocked by Tertiapin-Q (TPNQ), a ROMK channel inhibitor. The high potassium diet significantly increased the probability of ROMK channel current occurrence in the apical membrane of renal DCT2, and enhanced the activity of ROMK channel, compared to normal potassium diet (P < 0.01). Western blot results also demonstrated that the high potassium diet significantly up-regulated the protein expression levels of ROMK channels and epithelial sodium channel (ENaC), and down-regulated the protein expression level of Na⁺-Cl^- cotransporter (NCC). Moreover, the high potassium diet significantly increased urinary potassium excretion. These results suggest that the high potassium diet may activate the ROMK channels in the apical membrane of renal DCT2 and increase the urinary potassium excretion by up-regulating the expression of renal ROMK channels.
Potassium Channels, Inwardly Rectifying/metabolism* ; Kidney Tubules, Distal/metabolism* ; Potassium/metabolism* ; Epithelial Sodium Channels/metabolism* ; Diet

Virtually all of the dietary potassium intake is absorbed in the intestine, over 90% of which is excreted by the kidneys regarded as the most important organ of potassium excretion in the body. The renal excretion of potassium results primarily from the secretion of potassium by the principal cells in the aldosterone-sensitive distal nephron (ASDN), which is coupled to the reabsorption of Na⁺ by the epithelial Na⁺ channel (ENaC) located at the apical membrane of principal cells. When Na⁺ is transferred from the lumen into the cell by ENaC, the negativity in the lumen is relatively increased. K⁺ efflux, H⁺ efflux, and Cl^- influx are the 3 pathways that respond to Na⁺ influx, that is, all these 3 pathways are coupled to Na⁺ influx. In general, Na⁺ influx is equal to the sum of K⁺ efflux, H⁺ efflux, and Cl^- influx. Therefore, any alteration in Na⁺ influx, H⁺ efflux, or Cl^- influx can affect K⁺ efflux, thereby affecting the renal K⁺ excretion. Firstly, Na⁺ influx is affected by the expression level of ENaC, which is mainly regulated by the aldosterone-mineralocorticoid receptor (MR) pathway. ENaC gain-of-function mutations (Liddle syndrome, also known as pseudohyperaldosteronism), MR gain-of-function mutations (Geller syndrome), increased aldosterone levels (primary/secondary hyperaldosteronism), and increased cortisol (Cushing syndrome) or deoxycorticosterone (hypercortisolism) which also activate MR, can lead to up-regulation of ENaC expression, and increased Na⁺ reabsorption, K⁺ excretion, as well as H⁺ excretion, clinically manifested as hypertension, hypokalemia and alkalosis. Conversely, ENaC inactivating mutations (pseudohypoaldosteronism type 1b), MR inactivating mutations (pseudohypoaldosteronism type 1a), or decreased aldosterone levels (hypoaldosteronism) can cause decreased reabsorption of Na⁺ and decreased excretion of both K⁺ and H⁺, clinically manifested as hypotension, hyperkalemia, and acidosis. The ENaC inhibitors amiloride and Triamterene can cause manifestations resembling pseudohypoaldosteronism type 1b; MR antagonist spironolactone causes manifestations similar to pseudohypoaldosteronism type 1a. Secondly, Na⁺ influx is regulated by the distal delivery of water and sodium. Therefore, when loss-of-function mutations in Na⁺-K⁺-2Cl^- cotransporter (NKCC) expressed in the thick ascending limb of the loop and in Na⁺-Cl^- cotransporter (NCC) expressed in the distal convoluted tubule (Bartter syndrome and Gitelman syndrome, respectively) occur, the distal delivery of water and sodium increases, followed by an increase in the reabsorption of Na⁺ by ENaC at the collecting duct, as well as increased excretion of K⁺ and H⁺, clinically manifested as hypokalemia and alkalosis. Loop diuretics acting as NKCC inhibitors and thiazide diuretics acting as NCC inhibitors can cause manifestations resembling Bartter syndrome and Gitelman syndrome, respectively. Conversely, when the distal delivery of water and sodium is reduced (e.g., Gordon syndrome, also known as pseudohypoaldosteronism type 2), it is manifested as hypertension, hyperkalemia, and acidosis. Finally, when the distal delivery of non-chloride anions increases (e.g., proximal renal tubular acidosis and congenital chloride-losing diarrhea), the influx of Cl^- in the collecting duct decreases; or when the excretion of hydrogen ions by collecting duct intercalated cells is impaired (e.g., distal renal tubular acidosis), the efflux of H⁺ decreases. Both above conditions can lead to increased K⁺ secretion and hypokalemia. In this review, we focus on the regulatory mechanisms of renal potassium excretion and the corresponding diseases arising from dysregulation.
Humans ; Bartter Syndrome/metabolism* ; Pseudohypoaldosteronism/metabolism* ; Potassium/metabolism* ; Aldosterone/metabolism* ; Hypokalemia/metabolism* ; Gitelman Syndrome/metabolism* ; Hyperkalemia/metabolism* ; Clinical Relevance ; Epithelial Sodium Channels/metabolism* ; Kidney Tubules, Distal/metabolism* ; Sodium/metabolism* ; Hypertension ; Alkalosis/metabolism* ; Water/metabolism* ; Kidney/metabolism*

Hypertension is one of the strongest risk factors for cardiovascular diseases, cerebral stroke, and kidney failure. Lifestyle and nutrition are important factors that modulate blood pressure. Hypertension can be controlled by increasing physical activity, decreasing alcohol and sodium intake, and stopping tobacco smoking. Chronic kidney disease patients often have increased blood pressure, which indicates that kidney is one of the major organs responsible for blood pressure homeostasis. The decrease of renal sodium reabsorption and increase of diuresis induced by high potassium intake is critical for the blood pressure reduction. The beneficial effect of a high potassium diet on hypertension could be explained by decreased salt reabsorption by sodium-chloride cotransporter (NCC) in the distal convoluted tubule (DCT). In DCT cells, NCC activity is controlled by with-no-lysine kinases (WNKs) and its down-stream target kinases, Ste20-related proline-alanine-rich kinase (SPAK) and oxidative stress-responsive 1 (OSR1). The kinase activity of WNKs is inhibited by intracellular chloride ([Cl^-]_i) and WNK4 is known to be the major WNK positively regulating NCC. Based on our previous studies, high potassium intake reduces the basolateral potassium conductance, decreases the negativity of DCT basolateral membrane (depolarization), and increases [Cl^-]_i. High [Cl^-]_i inhibits WNK4-SPAK/OSR1 pathway, and thereby decreases NCC phosphorylation. In this review, we discuss the role of DCT in the blood pressure regulation by dietary potassium intake, which is the mechanism that has been best dissected so far.
Blood Pressure ; Diet ; Humans ; Kidney/metabolism* ; Kidney Tubules, Distal/metabolism* ; Phosphorylation ; Potassium/pharmacology* ; Protein Serine-Threonine Kinases ; Solute Carrier Family 12, Member 3/metabolism*

Perlman syndrome is a rare autosomal recessive congenital overgrowth syndrome caused by pathogenic variants of the DIS3L2 gene at 2q37 region. Clinically this syndrome is characterized by polyhydramnios, macrosomia, distinctive facial appearance, and renal dysplasia. Prognosis of the disease is poor, and survivors usually have mental delay and a high risk of developing Wilms tumor. At present, the pathogenesis of this disease is still poorly understood. This article intends to provide a review for this disease.
Female ; Fetal Macrosomia ; Humans ; Kidney Tubules, Proximal ; Pregnancy ; Syndrome ; Wilms Tumor

Adult ; Aged ; Aged, 80 and over ; Betacoronavirus ; Coronavirus Infections ; complications ; Female ; Glomerular Filtration Rate ; Glycosuria ; epidemiology ; Hospitalization ; Humans ; Hyponatremia ; epidemiology ; Kidney Tubules, Proximal ; physiopathology ; Male ; Middle Aged ; Pandemics ; Pneumonia, Viral ; complications ; Retrospective Studies

Drugs are a common cause of acute and chronic kidney disease and contribute to patient morbidity and increased healthcare utilization. Drug-induced nephrotoxicity is approximately 14% to 26% in adults and tends to increase among certain patients and/or with complex clinical conditions. Unfortunately, apart from conservative management, including drug withdrawal, no effective treatment is known for this condition. Therefore, in order to reduce the frequency of drug-induced nephrotoxicity, early recognition of renal toxicity and appropriate prevention strategies, such as understanding the exact mechanisms of renal injury, patient and drug-related risk factors, and preemptive measures are needed. In this review, we will present the mechanisms of drug-induced nephrotoxicity and general preventive strategies for clinical physicians.
Adult ; Delivery of Health Care ; Humans ; Kidney Tubules ; Pharmaceutical Preparations ; Renal Insufficiency ; Renal Insufficiency, Chronic ; Risk Factors

Objective Injured tubular reabsorption is highlighted as one of the causes of increased albuminuria in the early stage of diabetic nephropathy; however, the underlying mechanism has not been fully elucidated. In this study, we aimed to explore whether reducing inflammation and remodeling the insulin signaling pathway could improve albumin uptake of renal tubules. Methods 8-week-old male db/db mice (n=8), a type 2 diabetic nephropathy model, administered with nuclear factor kappa-B (NF-κB) inhibitor parthenolide (PTN, 1 mg/kg) intraperitoneally every other day for 8 weeks, were as the treatment group. Meanwhile, the age-matched male db/m mice (n=5) and db/db mice (n=8) were treated with saline as the control group and type 2 diabetic nephropathy group. When the mice were sacrificed, blood and urine were collected to examine homeostasis model assessment of insulin resistance (HOMA-IR) and urine albumin creatinine ratio, and kidney samples were used to analyze histopathologic changes with periodic acid-Schiff (PAS) staining, NF-κB p65, phosphorylation of AKT (p-AKT), amnionless and cubilin expressions with immunohistochemistry as well as western blot, and the albumin uptake of renal tubules by using immunofluorescence. In addition, HKC cells were divided into the insulin group treated with insulin alone, the TNF-α group treated with insulin and tumor necrosis factor (TNF-α), and the TNF-α+PTN group exposed to PTN, insulin and TNF-α. The levels of albumin uptake and expression levels of NF-κB p65, p-IRS-1/IRS-1, p-AKT/AKT, amnionless and cubilin in HKC cells were measured. Results Compared with the db/db group, the db/db+PTN group demonstrated decreased levels of HOMA-IR (36.83±14.09 vs. 31.07±28.05) and urine albumin creatinine ratio (190.3±7.3 vs. 143.0±97.6 mg/mmol); however, the differences were not statistically significant (P>0.05). Periodic acid-Schiff staining showed PTN could alleviate the glomerular hypertrophy and reduce the matrix in mesangial areas of db/db mice. The renal expression of NF-κB p65 was increased and p-AKT (s473) decreased in the db/db group compared with the db/m group (P<0.05). PTN significantly reduced the renal expression of NF-κB p65 and ameliorated the decline of p-AKT (s473) compared with the db/db group (P<0.05). Compared with the db/m group, the expression of amnionless and cubilin decreased and albumin uptake in tubules were reduced in the db/db group (P<0.05), and PTN could significantly increase the expression of cubilin (P<0.05), and improve albumin uptake in tubules. Insulin promoted albumin uptake and the expression of amnionless and cubilin in HKC cells (P<0.05). TNF-α stimulated the expression of NF-κB p65, increased p-IRS-1 (s307) and reduced p-AKT (s473) in HKC cells (P<0.05). In the TNF-α+PTN group, the expression of NF-κB p65 declined and p-IRS-1 (s307) and p-AKT (s473) were restored, compared with the TNF-α group (P<0.05). The expression of amnionless and cubilin decreased in the TNF-α group (P<0.05), and PTN could significantly increase the expression of cubilin (P<0.05). Conclusions Inflammation caused damage to insulin signaling, which reduced amnionless-cubilin expression and albumin uptake. PTN could reduce inflammation and remodel the impaired insulin signaling pathway, which promoted the expression of cubilin and albumin uptake. Our study can shed light on the role of inflammation in the reduction of albumin uptake of renal tubules in type 2 diabetic nephropathy.
Albumins/pharmacokinetics* ; Albuminuria/urine* ; Animals ; Anti-Inflammatory Agents, Non-Steroidal/pharmacology* ; Cell Line ; Creatinine/urine* ; Diabetes Mellitus, Type 2/complications* ; Diabetic Nephropathies/metabolism* ; Humans ; Insulin Resistance ; Kidney Tubules, Proximal/metabolism* ; Male ; Mice ; NF-kappa B/metabolism* ; Receptors, Cell Surface/metabolism* ; Sesquiterpenes/pharmacology*

In this study,in-depth systematic evaluation of rat of acute kidney injury(AKI) caused by renal arteriovenous ligation was conducted to better master and apply this model for drug research. Male SD rats of 2-3 months old were employed in this study.The left kidney was removed,and the right kidney received ligation for 40 min and reperfusion for 24 h. Serum creatinine(Crea),urea nitrogen(BUN) and the renal tissue sections were assayed as the basic indicators to evaluate their renal function. The mRNA expression of inflammatory necrosis factors and apoptotic factors was used to evaluate the mechanism of molecular pathophysiological changes. The results showed that the serum Crea and BUN caused by ligation of both renal arteries and veins were significantly higher than those of rats with renal artery ligation. After renal arteriovenous ligation for 40 min and reperfusion for 24 h in rats,the serum Crea of the rats varied from less than 100 μmol·L-1 to more than 430 μmol·L-1. Among them,5 rats showed less than 100 μmol·L-1 serum Crea,20 rats with 100-200 μmol·L-1 serum Crea and 12 rats with more than 430 μmol·L-1. Rats with serum Crea between 300-430 μmol·L-1 accounted for 66.3%(122/184) of the total number of the experiment rats. After 72 h reperfusion,serum Crea in the group of Crea 370-430 μmol·L-1 continued to increase,while the serum Crea in the group of Crea 200-300 μmol·L-1 and the group of Crea 300-370 μmol·L-1 recovered quickly. No matter serum Crea was elevated or decreased,the renal tubules showed pathological changes such as vacuolar degeneration or even necrosis. The mRNA expression levels of Toll-like receptor(TLR4),tumor necrosis factor(TNF-α) and interleukin(IL-6) in renal tissueswere significantly up-regulated,and the effect was most obvious in the group of serum Crea 370-430 μmol·L-1. The study indicated that the model for AKI caused by renal arteriovenous ligation and reperfusion is easy to operate,and the serum Crea and BUN have the characteristics of continuous increase,beneficial to the observation of drug effects. This acute kidney injury is mainly related to the pathophysiological response of inflammatory necrosis.
Acute Kidney Injury ; pathology ; Animals ; Blood Urea Nitrogen ; Creatinine ; blood ; Disease Models, Animal ; Kidney ; pathology ; Kidney Tubules ; pathology ; Ligation ; Male ; Rats ; Rats, Sprague-Dawley ; Renal Artery ; Reperfusion Injury

Shenkang injection (SKI) is a classic prescription composed of Radix Astragali, rhubarb, Astragalus, Safflower, and Salvia. This treatment was approved by the State Food and Drug Administration of China in 1999 for treatment of chronic kidney diseases based on good efficacy and safety. This study aimed to investigate the protective effect of SKI against high glucose (HG)-induced renal tubular cell senescence and its underlying mechanism. Primary renal proximal tubule epithelial cells were cultured in (1) control medium (control group), medium containing 5 mmol/L glucose; (2) mannitol medium (mannitol group), medium containing 5 mmol/L glucose, and 25 mmol/L mannitol; (3) HG medium (HG group) containing 30 mmol/L glucose; (4) SKI treatment at high (200 mg/L), medium (100 mg/L), or low (50 mg/L) concentration in HG medium (HG + SKI group); or (5) 200 mg/L SKI treatment in control medium (control + SKI group) for 72 h. HG-induced senescent cells showed the emergence of senescence associated heterochromatin foci, up-regulation of P16 and cyclin D1, increased senescence-associated β-galactosidase activity, and elevated expression of membrane decoy receptor 2. SKI treatment potently prevented these changes in a dose-independent manner. SKI treatment prevented HG-induced up-regulation of pro-senescence molecule mammalian target of rapamycin and p66Shc and down-regulation of anti-senescence molecules klotho, sirt1, and peroxisome proliferator-activated receptor-g in renal tubular epithelial cells. SKI may be a novel strategy for protecting against HG-induced renal tubular cell senescence in treatment of diabetic nephropathy.
Animals ; Cells, Cultured ; Cellular Senescence ; drug effects ; Cyclin D1 ; metabolism ; Cyclin-Dependent Kinase Inhibitor p16 ; metabolism ; Diabetic Nephropathies ; drug therapy ; Drugs, Chinese Herbal ; pharmacology ; Epithelial Cells ; drug effects ; metabolism ; Glucose ; Kidney Tubules, Proximal ; physiopathology ; Male ; Mice ; Mice, Inbred C57BL

OBJECTIVE: To investigate the effect of blocking pannexin-1 against acute kidney injury induced by cisplatin. METHODS: Twenty-six male C57BL/6 mice aged 6-8 weeks were randomly divided into control group, cisplatin model (Cis) group and cisplatin + carbenoxolone treatment group (Cis + CBX). In Cis group and Cis + CBX group, the mice were injected intraperitoneally with 20 mg/kg of cisplatin and with CBX (20 mg/kg) at 30 min before and 24 and 48 h after cisplatin inhjection, respectively. All the mice were sacrificed at 72 h after cisplatin injection, and plasma and kidney samples were collected for testing mRNA and protein expression levels of pannexin-1 in the renal tissue using RT-qPCR and Western blotting and for detecting plasma creatinine and BUN levels; the pathological changes in the renal tissues were observed using Periodic Acid-Schiff staining. The expression of kidney injury molecule 1 (KIM-1) was examined using immunohistochemistry and the mRNA expressions of KIM-1 and neutrophil gelatinase- related lipid transport protein (NGAL) were detected by RT-qPCR to evaluate the injuries of the renal tubules. The infiltration of F4/80-positive macrophages and CD4-positive T cells were observed by immunofluorescence. In the experiment, human proximal tubule epithelial cell line HK-2 was stimulated with 50 μmol/L cisplatin to establish a cell model of acute kidney injury, and the mRNA and protein expressions of pannexin-1 were detected by RT-qPCR and Western blotting at 4, 6, 12, 18 and 24 h after the stimulation. RESULTS: Compared with the control mice, the cisplatin-treated mice showed significantly up-regulated protein levels ( < 0.05) and mRNA levels ( < 0.005) of pannexin-1 in the kidney tissue. Cisplatin stimulation also caused significant increases in the protein levels ( < 0.005) and mRNA levels ( < 0.005) of pannexin-1 in cultured HK-2 cells. Compared with cisplatin-treated mice, the mice treated with both cisplatin and the pannexin-1 inhibitor CBX showed obviously lessened kidney pathologies and milder renal tubular injuries with significantly reduced plasma BUN and Scr levels ( < 0.01), expressions of KIM-1 and NGAL in the kidney ( < 0.05), and infiltration of F4/80-positive macrophages ( < 0.01) and CD4- positive T cells ( < 0.05) in the kidney tissues. CONCLUSIONS In cisplatin induced acute kidney injury mice model, Pannexin-1 expression is up-regulated in the kidneys tissue, and blocking pannexin-1 alleviates the acute kidney injury reducing renal inflammatory cell infiltration.
Acute Kidney Injury ; drug therapy ; metabolism ; Animals ; Cisplatin ; pharmacology ; Connexins ; drug effects ; metabolism ; Cross-Linking Reagents ; pharmacology ; Humans ; Kidney ; Kidney Tubules ; Male ; Mice ; Mice, Inbred C57BL ; Nerve Tissue Proteins ; drug effects ; metabolism ; Random Allocation